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Can hibernators sense and evade fires? Olfactory acuity and locomotor performance during deep torpor

Abstract

Increased habitat fragmentation, global warming and other human activities have caused a rise in the frequency of wildfires worldwide. To reduce the risks of uncontrollable fires, prescribed burns are generally conducted during the colder months of the year, a time when in many mammals torpor is expressed regularly. Torpor is crucial for energy conservation, but the low body temperatures (T b) are associated with a decreased responsiveness and torpid animals might therefore face an increased mortality risk during fires. We tested whether hibernators in deep torpor (a) can respond to the smell of smoke and (b) can climb to avoid fires at T bs below normothermic levels. Our data show that torpid eastern pygmy-possums (Cercartetus nanus) are able to detect smoke and also can climb. All males aroused from torpor when the smoke stimulus was presented at an ambient temperature (T a) of 15 °C (T b ∼18 °C), whereas females only raised their heads. The responses were less pronounced at T a 10 °C. The first coordinated movement of possums along a branch was observed at a mean T b of 15.6 °C, and animals were even able to climb their prehensile tail when they reached a mean T b of 24.4 °C. Our study shows that hibernators can sense smoke and move at low T b. However, our data also illustrate that at T b ≤13 °C, C. nanus show decreased responsiveness and locomotor performance and highlight that prescribed burns during winter should be avoided on very cold days to allow torpid animals enough time to respond.

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Acknowledgments

We thank Arne Müller and Chris Wacker for the assistance in animal maintenance. The project was supported by grants from the German Academic Exchange Service and the A.F.W. Schimper Stiftung für ökologische Forschung to JN, a University of New England Postdoctoral Research Fellowship to CS, by the Australian Research Council and the University of New England to FG and by the French Ministry of Agriculture, Agrifood and Forestry and by the Region Auvergne (France) to MD.

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Correspondence to Julia Nowack.

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Communicated by: Sven Thatje

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Nowack, J., Delesalle, M., Stawski, C. et al. Can hibernators sense and evade fires? Olfactory acuity and locomotor performance during deep torpor. Sci Nat 103, 73 (2016). https://doi.org/10.1007/s00114-016-1396-6

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  • Keywords
  • Cercartetus nanus
  • Torpor
  • Locomotion
  • Sensory perception
  • Smell